Shop OBEX P1 Docs P2 Docs Learn Events
Water sensing — Parallax Forums

Water sensing

AImanAIman Posts: 531
edited 2007-01-15 15:26 in BASIC Stamp
Hey all. I have an interesting concept for you to chew on.

One of my robots I use to sense a level of water. When the water hits a certain level the robot shuts the water off, the container filled is about the size of a plastic gallon milk jug.

There are a zillion ways to do this, however I am interested in what others think would work.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2006-12-21 15:24
    Weight is a common way of sensing whether a container is full. You can use anything from a strain gauge to a simple lever and microswitch with a counterweight.
  • JonathanJonathan Posts: 1,023
    edited 2006-12-21 16:23
    If you need to have an idea as to how full...

    You can·glue a strip of foil on the container, and put a contact in the water. The strip of metal/container/water will act as a capacitor and the value will vary with how full. Use RCTIME to see how full.

    If the container is in a non humid enviorment, you could also try an ultrasonic sensor.

    Or as mentioned above, a strain gauge. Parallax sells one, and you should be able to get an idea of how full the container is.

    If it's just for fun, you can use a piece of conductive foam to make a pressure sensor. The kind that IC's are shipped with. If you make a sandwich with a layer of PC board, a chunk of foam and another layer of PCB board, you will see that the resistance varies when compressed. Use as part of a voltage divider. The drawback is that the foam compresses over time.

    Just some silly ideas...

    Jonathan

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • LSBLSB Posts: 175
    edited 2006-12-21 16:55
    Take a look at the Qprox and QTouch capacitive touch sensor. Parallax sells a binary version, and there are versions that output PWM for variable input as well.
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2006-12-21 18:41
    I'm not clear on the proximity of the robot to the water and the container. Maybe the robot wanders around and finds the container(s) at random locations. Should the sensing avoid preparation of the container in advance, some sort of dipstick arm or "remote" sensing? I guess the robot does not have to avoid water, in the sense of getting its feet wet like a beachwalker.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Tracy Allen
    www.emesystems.com
  • AImanAIman Posts: 531
    edited 2006-12-22 02:05
    I have a couple of different things I am doing with water. The one in mind for this thread is a robot that fills a water jug from the sink.

    Currently its sensors are·based on springs and microswitches, but weight would work and possible sonar if the water was allowed to sit a few seconds.


    One of the parallax guys told me about a fish tank they have with IR sensors set up so that when the fish swims past an IR the tank wanders around the office.
  • John R.John R. Posts: 1,376
    edited 2006-12-22 15:53
    How about just a simple float switch. If the mouth of the jug is big enough, you could even make a DIY switch with a ping pong ball attached to the arm of small lever micro-switch. I've also used some commercial units with a ring float around a tube. The tube has a reed switch inside, and the float has a magnet.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    John R.

    8 + 8 = 10
  • Tim-MTim-M Posts: 522
    edited 2006-12-22 16:39
    To expand on John R's thoughts regarding commercial ring-float around a tube with·a reed switch... you could have several reed switches within the tube at various levels, so that the float would trigger each as it passes up and down·and give you a water level indication.

    Tim
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2006-12-22 17:53
    >>robot that fills a water jug from the sink

    This robot should be constructed in the form of a broom, walking on the tips of bifurcated bristles. One arm carries a small bucket as it goes to a fro from sink to jug. The other arm reaches into the jug with its finger and feels for water. No?--Continue trip with more water. Yes?--Stop filling. Leave out Mickey Mouse and the axe. However, the wizard behind all this should probably stick around, just in case...

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Tracy Allen
    www.emesystems.com
  • JonathanJonathan Posts: 1,023
    edited 2006-12-22 20:44
    or you could add a rotary encoder with the float idea, and be able to determine the level of the water.

    Jonathan

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • Steph LindsaySteph Lindsay Posts: 767
    edited 2006-12-22 21:38
    Tracy, there is laughter ringing in the Education office; we can hear the Fantasia music too!

    -Stephanie Lindsay
    Editor, Parallax Inc.
  • AImanAIman Posts: 531
    edited 2006-12-24 04:18
    Well, hey, if Mickey can do it why cant I?

    I like the idea of the float with reed switches or a float with a microswitch.
  • Sarten-XSarten-X Posts: 32
    edited 2006-12-25 06:32
    Two stripped wires held separate by a bit of tape. Add a few spoonfuls of table salt to the bottom of the jug, and you've got yourself a water sensor. Or if you're using sufficiently-ionized water already, it may work to eliminate the salt.
    For illustration purposes:
    | |     | |
| |     | |
| |     | |
| |     | |
|_|_____|_|
| |     | |  <- Tape wide enough to stop the ends from touching or holding a drop
|_|_____|_|
| |     | |
| |     | |  <- Unstripped long enough to stop stray drops from spanning the gap
| |     | |
 |       |   <- stripped ends
 |       |

    It will act like a switch that closes when the water level reaches the stripped ends.
  • AImanAIman Posts: 531
    edited 2007-01-15 15:26
    My end result was a whisker attached to a float. Crude but effective.
Sign In or Register to comment.